Hydraulic pick

ABSTRACT

A piston rod with a piston, against which a displaceable valve ring, a short, axially rigid striking pin, guided in a bush, and a pressure transformer piston are set, is immovably placed in one part of the supporting housing. A working tool is placed in the second part of the supporting housing in a tool bush protected on the outside by a lower sealing cover to prevent corrosion. A gas chamber is set up under the supporting housing, the pressure transformer piston and the striking pin. A pressure transformer cylinder and an equalizing chamber are formed between the piston rod and tfe pressure transformer piston. The striking pin is driven by a working fluid under pressure, which is distributed by a system of channels in the piston rod. The striking pin is driven onto the working tool in a striking action by high-pressure gas, which is pressurized in the gas chamber. The movement of the striking pin is controlled by a switching element, fitted in the piston rod, and a valve ring, pushed onto the piston rod surface. It is assisted by the pressure transformer, which eliminates pressure peaks of the working fluid.

The solution concerns hydraulic pick that falls into category ofportable drifting devices actuating by stroke a driven by pressureliquid. It is a pick of piston type, where on working tool—cutterhammers impulse element—firing pin.

STATE-OF-THE-ART

Known solutions are based on hydraulic steering of striking pin whichhas the shape of continuous piston rod. Piston rod has in the middlepart increased diameter which takes over the function of slightly sealedpiston by gap in the cylinder. Because the striking pin is aftereventual touch of striking pin's piston part with cylinder in placingstatically designed, this gap has to be sufficiently big what causes bigflow losses. This has the biggest influence on decrease in efficiency ofpicks in present world production. Inlet of pressure oil is led intocylinder's working chambers from steering through supporting housing bychannels that are decreasing effectiveness of picks by their hydraulicresistance, especially by movement of striking pin into stroke. Impulsefor switching of switching element in upper position is obtained fromcontrol channel in cylinder. This channel does not enable sealing ofstriking pin's piston by a cup. Therefore is the diameter of strikingpin as small as possible. But then for required weight increases thelength of striking pin. This results in decreasing of axial strength athereby also strength of stroke by the same achieved speed.

Supporting housings of picks are from assembling reasons and alsobecause of absorption of no-load strokes, respectively for absorption ofresidual energy after sudden penetration through barrier, designed frommore parts, joint by long screws that are by their elasticity decreasingdestructive impacts on bottom part of pick and on outrigger ofindustrial machine. These screws are stressed to such extent that comesnot only to plastic deformation of nuts, but also to breakage of screwsthemselves. Plastic deformation of nuts and screws is eliminated inoperation by continuous retightening of nuts. Residual energy of workingtool is absorbed by cross pin what damages is placement, cutout fromtool and also damages the pin itself. Diminished shaft of working toolcauses its breakage by break open.

Working tool is placed in bottom part of pick in thermally hardenedsteel cases. Here comes to seizing of placement with progressiveincrease in allowance of placement. The result is penetration of dustand impurities into its placement and also last but not leastorigination of eccentric stroke of striking pin to head of tool. Forwork under water is therefore supplied into area of tool's placementcompressed air. Nowadays are already known solutions where is thisproblem solved by flexible placement by contemporary interval supply ofoil from aggregate of industrial machine.

Compressive force of industrial machine to pick is transferred byworking tool to pick's part by annulus surface which arose by decreasingof tool head's diameter. But that damps tool's head, what is usually thereason of its hammering or abruption.

Picks in bulk are mechanically protected by their placement into othercase which will be fixed by adapter to industrial machine. There areknown solutions, where in order to decrease in negative impact onindustrial machine, the pick is placed into box flexibly or is construedin such way that no-load strokes will be prevented. This concept workswith permanent leakage flow and by run of function of this member willbe the pressure in hydraulic system increased to value of safetypressure what has negative impact on whole hydraulic system bycontemporary overheating of working liquid. Equally are known solutions,where is this box embedded by sound baffle material, to decrease outernoise level of pick.

Common sign of picks from worldwide production is their bigtechnological severity, weight, dimensionality and sensitivity to roughhandling.

SUBJECT MATTER OF THE INVENTION

Mentioned negatives are removed by solution according to invention withinverse concept where striking pin is cylinder placed on piston rod thatis firmly connected with supporting housing. The controlling is ahydraulic flip-flop circuit that reacts only to both extreme positionsof striking pin. Switching element, placed in piston rod, switches thedirection of flow of pressure working liquid with high speed. In theextreme positions is hydraulically locked. In case of working tool inextra-work position, the pressure of liquid in system will be decreased,what will cause the interruption of pick's function. There does not cometo no-load strokes and working liquid is not overheated.

High pressure accumulator, used in other picks, is here replaced bypressure transformer with cylinder and piston. The piston has from oneside low pressure gas chamber, shared with striking pin and from otherside equalizing chamber that is connected with gas chamber only instarting position. Pressure transformer's cylinder is connected to inletof pressure working liquid and in consequence of parallel movement ofpressure transformer's piston with striking pin, secures almost constantpressure in hydraulic system and by its regulated damping in dependenceon flow, removes also vibrations from the movement of striking pin.

The basis of hydraulic pick according to the invention consists in thefact that in upper part of rotary supporting housing is immovable placedpiston rod with piston, on which is slipped-on the piston of pressuretransformer, movable valve ring and striking pin, loaded into bushplaced to inner wall of supporting housing. In the piston rod body iscreated continuous inlet channel with taps, terminated by controlchannel and continuous return duct with tap, through that flows thepressure working liquid. In the piston rod are created also other holesfrom surface to control channel, in which is placed the switchingelement with pan construction. Valve ring equipped by inner relive, isslipped-on the piston rod by its lower side in the area of its decreaseddiameter. Upper side of valve ring is slipped-on the body of piston rodwith non-reduced diameter. Into cavity in the ring, which arose by itsrelive, is into it flowed the first channel from control channel.

Into supporting housing is from the other, lower side, inserted theworking tool, which is placed in bush in such way, that there are nopullbacks. From outer side is bush protected against workingenvironment, sealed and closed by cover. Short solid striking pin evokesbigger strength of stroke, and thus the diameter of working tool's headis inversely increased. The tool does not have any damping for safetypin. The new shape of tool is resistant against breakage by breakopening. Pick allows the work under water without need for inlet ofcompressed air. In case of sudden penetration through barrier is thetool axially spring-loaded. Against origination of no-load strokes isthe pick equipped by safety circuit, which contrary to known solutionswill not increase the pressure in hydraulic system up to value of safetypressure, if the striking pin will come to extra-work position, but onthe contrary the pressure will be decreased, whereby the function ofpick will be immediately interrupted. Controlling hydraulic flip-flopcircuit is switched by full speed, in extreme positions is hydraulicallybraked and is not the function of hydraulic resistances. Very toilsomenoise damping of pick, until now realized on the pick's surface by itsplacement into box, is brought forward into pick, directly to the sourceof acoustic performance (striking pin—working tool). Other advantage aresmall dimensions and less than half of weight in comparison with knownpicks, what extends its usage to larger ranger of industrial machines.Pick does not contain screw connections. Pick parts are after theirassembly into bulk connected by sufficiently big forces, activated bypressure of filling gas, usually by nitrogen. Pick does not require anymaintenance. Greasing of working tool's bushings is automatic from lowpressure return tap.

VIEW OF THE FIGURES IN THE DRAWINGS

FIG. 1 is schematic representation of hydraulic pick from first exampleof realization in longitudinal section. On FIG. 2 is in the sectionmagnified detail of control mechanism from FIG. 1. On FIG. 3 isschematic representation of pick in longitudinal section with othersecurity circuit according to second example of realization.

EXAMPLES OF ACCOMPLISHED INVENTION

Hydraulic pick is assembled from four main parts that are: monolithicrotary supporting housing 1, piston rod 2, striking pin 3 and workingtool 4. In supporting housing 1 is non-movable placed piston rod 2,secured against protrusion by safety ring 5. On the piston rod 2 isslipped-on movable striking pin 3, executed as rotary body, axiallybored according to piston rod's diameter 2, with inner removal, whichcavity is after slip-on of striking pin 3 on piston rod 2 divided bysealing piston 21 to first chamber 41 and second chamber 42. In the areaof first chamber 41 has the piston rod 2 in one part decreased outerdiameter. In this area is on the piston rod 2 slipped-on valve ring 23.The length of valve ring 23 is bigger than length of segment, on whichhas the piston rod 2 decreased outer diameter. To this situation isadjusted the valve ring 23 in such way, that on the side which is closerto piston 21 has his face axial hole equivalent to diameter of pistonrod 2 in its non-tapered part. On opposed end has the valve ring 23 itsface with axial hole equivalent to diameter of piston rod 2 in itstapered part. Between both terminal faces has the valve ring 23 insiderelive, by which is after slip-on the valve ring 23 on piston rod 2created between those two bodies the cavity 46 in the ring. In thepiston rod 2 is created continuous inlet channel 6 with first tap 7,third tap 9 and fourth tap 10. To the end of inlet channel 6 isconnected next space with inserted light switching element 20 with panconstruction. Switching element 20 is executed in ring shape withgraduated outer and inner diameters in such way that overall surface ofits bottom (on Fig. left) faces is bigger than surface of upper (on Fig.right) faces. In switching element 20 is executed the duct 14 fillingduct 15. After insertion of switching element 20 are created in statednext space four cavities: lower 47, small 48, middle 49 and upper cavity50. Lower cavity 47 is connected with cavity 46 in the ring by firstchannel 16. Small cavity 48 is connected with the surface of piston rod2 in first chamber 41 by lower nozzle 22 and second channel 17. Intomiddle cavity 49 is loaded fourth tap 10 of inlet channel 6. From theside of switching element 20 is connected with it the filling duct 15.Upper cavity 50 is connected with inlet channel 6 through its third tap9 and with the surface of piston rod 2 is connected with fifth channel31 and upper nozzle 11. To switching element 20 is from the surface ofpiston rod 2 created on both sides of piston 21 a channel: from firstchamber 41 is it the third channel 18, from second chamber 42 is it thefourth channel 19. Through third channel 18 and duct 14 is first chamber41 permanently connected with return duct 12, created in piston rod 2.

Striking pin 3 is loaded into non-metal sealed axially sliding bush 24,slipped-on into supporting housing 1. In upper (right) part of pistonrod 2 is further assembled low-weight pressure transformer, byconnection of bell piston 25, sealed cylinder 43 and equalizing chamber44 in such way, that the cylinder 43 is made of piston's walls 25 andpiston rod 2 and is connected to first tap 7 of inlet channel 6. Sealedequalizing chamber 44 is created between piston 25 and piston rod'scover 2. In the area delimited by supporting housing 1, bush 24,striking pin 3, piston rod 2 and pressure transformer's piston 25 iscreated first gas chamber 45. In basic position of pressuretransformer's piston 25 is equalizing chamber 44 interconnected with gaschamber 45 by connecting channel 26. Working tool 4 is in supportinghousing 1 placed through non-metal tool bush 27 that is in this exampleof realization made as three-piece 27.1, 27.2, and 27.3, whereby itsmiddle part consists of spring-loading insertion 27.2. Tool bush 27 isagainst tool 4 sealed by floating metal stearing ring 28 equipped bysealing, which is against supporting housing 1 axially non-movable.Lower sealing cover 29 is secured against protrusion by safety ring 30with constant preload implied by strength of gas pressure in gas chamber45. Sealing of bushes 27 against supporting housing 1, bush 24 againstsupporting housing 1 and striking pin 3, striking pin 3 against pistonrod 2, piston 21 against strikng pin 3, pressure transformer's piston 25against piston rod 2 ad piston rod 2 against supporting housing 1 isachieved by non-drawn sealing cups. Hydraulic pick described in exampleof realization is built-up without screw connections.

Pick is equipped by safety circuit made by connection of drilling 51with inlet channel 6 through first safety channel 53 and with returnduct 12 through second safety channel 54. Drilling 51 is made frombottom face of piston rod 2 into its inner space in direction oflongitudinal axis of piston rod 2 and into it is inserted movable carpel52.

Into gas chamber 45 is before usage of hydraulic pick pushed gas toneeded pressure through non-drawn channel and cap in piston rod 2.Compressed gas pushes out the striking pin 3 into position, where itleans against the tool bush 27. By this move defers also the head ofworking tool 4 from face of piston rod 2. The body of striking pin 3will cover upper nozzle 11 and fifth channel 31. Working liquid acts onthe bottom of drilling 51 by pressure to carpel 52, which pushes outinto permanent contact with working tool 4. As far as the working tool 4is not leaned against working object (or other barrier), the strikingpin 3 will push it from pick out in such extent, that carpel 52, whichfollows the movement of working tool 4, will expose at its opposite end,until then by it closed connection of inlet channel 6 with return duct12 through first and second safety channel 53, 54. In that moment willbe lost in pick working pressure of liquid, if there was any. Inconsequence of this interconnection is the pick non-functional. Bypushing the working tool 4 into pick—by pressure of industrial machineto working subject—will be pushed also carpel 52 into piston rod 2,until the connection of inlet channel 6 with return duct 12 will beinterrupted in drilling 51. In taps 7 to 10 of inlet channel 6 will bethe pressure increased. Cavity 46 in ring will be through first channel16 filled by pressure working liquid which will move the valve ring 23into lower (left) position up to stop position. In this position isthrough lower nozzle 22 and second channel 17 connected small chamber 48with first chamber 41. As the first chamber 41 is permanently connectedwith return duct 12, without increased pressure stays also the smallcavity 48. Through fourth tap 10 and third tap 9 will be increased alsothe pressure in middle cavity 49 and upper cavity 50. On face areas ofswitching element 20 will arose in this way unbalance of strengths,which will steer the switching element 20 into fast movement towardslower cavity 47. During it the working liquid flows from small cavity 48through second channel 17 and lower nozzle 22 into first chamber 41. Bycovering of second channel 17 is increased the pressure in small cavity,following that the switching element 20 intensively starts to brake.Turnover of switching element 20 will be finished with small speed bydischarge of small cavity 48 into first chamber 41 only through lowernozzle 22. During movement of switching element 20 will connect thefilling duct 15 with fourth channel 19 and interrupt the connection offourth channel 19 with duct 14 of switching element 20. In secondchamber 42 will be increased the pressure, which will initiate themovement of striking pin 3 towards gas chamber 45 against gas pressure.By slow start of heavy striking pin 3 will prevent the increase ofpressure tip of cylinder 43 of light pressure transformer, which willabsorb the difference from constant flow of working liquid supplied byindustrial machine. Piston 25 of pressure transformer is by that movedagainst the movement of striking pin 3. After run of striking pin's job3 to speed corresponding with supplied flow, the piston 25 of pressuretransformer will following increase in gas pressure in gas chamber 45stop and consequently will start to return into original position.Working liquid that now flows from cylinder 43 of pressure transformerthrough first tap 7 will be added to the flow supplied by industrialmachine. By this will be further increased the sped of strikng pin 3.Reliable return of pressure transformer's piston 25 into originalposition assures hydraulic damping supported by cooperation ofequalizing chamber 44. Following that the striking pin 3 decreasescontinuously the speed to the value corresponding to flow of liquid fromindustrial machine, by which it is approaching the upper turning back offiring stroke. By this movement the face of striking pin 3 will befastened in first chamber 41 of valve ring 23 and is drifting with it.When will be by this movement of valve ring 23 connected the lowernozzle 22 with cavity 46 in ring and second channel 17 will cover thebody of valve ring 23, the pressure in small cavity 48 will beincreased. Because the surface of faces of switching element 20 inbottom cavity 47 and in small cavity 48 is in total bigger than surfaceof its faces in middle cavity 49 and upper cavity 50, even though thatall cavities are under high pressure of working liquid, the switchingelement 20 will move itself towards upper cavity 50. The speed of itsmovement will jump to higher value after connection of second channel 17with cavity 46 in ring. During this movement the second chamber 42 willbe detached from inlet channel 6 and connects to first chamber 41through fourth channel 19, duct 14 and third channel 18. Interconnectionof second chamber 42 with first chamber 41 occurs by filling of smallcavity 48 with working liquid through second channel 17. Intensivedeceleration and braking of switching element 20 in upper (right)position will be made by upper nozzle 11 after previous closing of fifthchannel 31 by switching element 20. After suspension of driving power insecond chamber 42, the movement of striking pin 3 will be in actualdirection stopped and following overpressure of gas in gas chamber 45will turn in opposite direction. At the same time because of pressureimpact in cavity 46 in ring will be the valve ring 23 returned to leftstop and will expose the second channel 17 and lower nozzle 22, by thatwill be the pressure in small cavity 48 decreased. Low pressure is alsoin upper cavity 50, because that is by fifth channel 31 and upper nozzle11 connected with second chamber 42. Because the actuating surface ofswitching element 20 in lower cavity 47 is bigger than actuating surfaceof its face in middle cavity 49, the switching element 20 will stay inreached position almost during whole time of striking pin's 3 movementstowards working tool 4. Immediately before stroke, when the fifthchannel 31 will be covered by striking pin 3 the pressure in uppercavity 50 will be increased, that again starts the switching element 20and for whole cycle begins the repeating. During movement of strikingpin 3 towards working tool 4 does not flow into return duct 12 anyworking liquid, therefore the second chamber 42, first chamber 41, smallcavity 48 and return duct 12 are completely without pressure. Fullamount of working liquid supplied by industrial machine flows only intopressure transformer's cylinder 43. Following that the pressuretransformer's piston 25 moves concurrent with striking pin 3. Thisresults into deceleration of decrease in gas pressure in gas chamber 45and increase in speed of striking pin 3. If the working tool pushes onpick, than during the movement of striking pin 3 into stroke, the headof working tool 4 leans against bottom face of piston rod 2, by that isprevented interconnection of inlet channel 6 with return duct 12 throughrelive 51. After stroke of strikng pin 3 to the head of working tool 4,the kinetic energy from flexible impact is transferred up to the tip ofworking tool 4. In the case of sudden penetration through barrier, thehead of working tool hits the spring loaded insertion 27.2, whichcontinuously absorbs the residual energy of working tool. Striking pin 3will stay leaned against the bush 27.1 and the operation of pick isinterrupted. Return to operation of pick is possible only after repeatedpin down of industrial machine to pick through working tool 4.

In other example of realization is safety circuit made from second tap8, drilled from inlet channel 6 to the surface of piston rod 2, returntap 13, lead from return duct 12 to the surface of piston rod 2 and fromsafety chamber 40, made from inner space in upper part of striking pin3. Second tap 8 and also return tap 13 are created in one plain uprightto longitudinal axis of pick. Other arrangement of pick is the same asthat which is shown on previous example.

Into gas chamber 45 is before usage of hydraulic pick pressed the gas toneeded pressure through non-drawn channel and cap in piston rod 2.Pressed gas will push the striking pin 3 into position, in which it willlean against the bush 27. By this movement also the head of working tool4 defers from the face of piston rod 2. Body of striking pin 3 willcover the upper nozzle 11 and fifth channel 31. Safety chamber 40,second tap 8 and return tap 13 will connect the inlet channel 6 withreturn duct 12. Following this interconnection is the picknon-functional. By pushing of working tool 4 into pick, will be frompressure of industrial machine to working subject pushed also the safetychamber 40. Connection of inlet channel 6 with return duct 12 will be bythis interrupted. In taps 7 to 10 of inlet channel 6 will be thepressure increased. The cavity 46 in ring will be through first channel16 filled by pressure working liquid, which will move the valve ring 23into lower (left) position up to stop position. By that will be startedthe operation of pick described in the first example of realization.

Function of safety circuit will be equally applied also by penetrationthrough working subject. Working tool 4 will be stopped. Pick does notbeat with no-load.

Advantage of hydraulic picks according to the invention is markedlyincreased working output following high effectiveness reaching values90% and increased strength of stroke induced by multiply axial strengthof striking pin 3. By new construction shape of working tool 4 and bythe way of its placement into solid smooth monolithic body withoutholes, with sleeve for anchoring of pick to industrial machine throughadapter, are the picks designed for heaviest conditions withoutlimitations of works. High speed of striking pin's 3 switching in bottomposition markedly decreases the impulse of slip-in strength. Smalldimensions and weight of pick and high resistance against damage allowsto use one size of pick for all industrial machines up to weight of 12.5t. Supporting housing 1 is just one rotary unit without screwconnections and lateral holes.

1. Hydraulic pick made of monolithic rotary supporting housing,cylindrical piston rod, rotary striking pin and rotary working tool,with inlet and outlet of pressure liquid, wherein in the part ofsupporting housing is non-movably placed piston rod with piston, onwhich is slipped-on movable valve ring, short and axially solid strikingpin, led in bush of striking pin and pressure transtormer's piston,whereby in second part of supporting housing is inserted working tool,placed without pullbacks in tool bush, which is protected from outerside by lower sealing cover, whereby by such arrangement is betweensupporting housing, pressure transformer's piston and striking pincreated gas chamber and between piston rod and pressure transformer'spiston is created pressure transformer's cylinder and equalizingchamber, whereby between gas chamber and equalizing chamber is createdconnecting channel.
 2. Hydraulic pick according to claim 1, wherein thestriking pin is a rotary body drilled in axis according to piston rod'sdiameter and created together with inner relive in such way that byslipped-on striking pin on the piston rod is created closed hollowspace, which is by piston divided to first chamber and second chamber.3. Hydraulic pick according to claim 1, wherein the piston rod has inthe area of first chamber on the surface continuous segment with limitedlength with diminished outer diameter, in which is slipped-on it valvering with bigger length than is the length of the segment withdiminished outer diameter of piston rod, therefore is made as hollowannulus with non-equal diameters of loading to piston rod, which is bybigger diameter on the face closer to the piston slipped-on the outersurface of piston rod in its non-diminished part, whereby by innerrelive of valve ring and with the surface piston rod is created closedcavity in ring.
 4. Hydraulic drilling hammer according to claim 1,wherein in inner space of piston rod are from its face created twocontinuous channels: return duct, permanently connected with firstchamber and equipped by return tap led to the surface of piston rod andinlet channel, equipped by first tap, third tap and fourth tap, to whichend is connected the lower cavity of space with inserted switchingelement, by which is in this space created yet small cavity, middlecavity and upper cavity, whereby the lower cavity is connected withfirst channel with cavity in ring, small cavity is connected with thesurface of piston rod in first chamber, lower nozzle and second channel,into middle cavity is led fourth tap of inlet channel and upper cavityis connected with third tap of inlet channel and fifth channel and uppernozzle is connected with the surface of piston rod, on which is led alsothe first tap of inlet channel, which is led into pressure transformer'scylinder, whereby from the surface of piston rod is to the switchingelement created within space of second chamber fourth channel and withinspace of first chamber third channel, so the lower nozzle, secondchannel and third channel are in piston rod created at the same side ofpiston and fourth channel, fifth channel and upper nozzle are created onthe opposite side of piston.
 5. Hydraulic pick according to claim 1,wherein the switching element is made with the ring shape with gradedouter and inner diameters in such way, that overall surface of itsbottom faces is bigger than the surface of its upper faces, whereby isin this ring created duct and filling duct.
 6. Hydraulic pick accordingto claim 1, wherein the bush of striking pin and also the tool bush areadvantageously non-metal, placement of working tool and striking pin isflexible, whereby the working tool and also striking pin are in thelower position spring-loaded.
 7. Hydraulic pick according to claim 1,wherein the sound baffling material is applied in the inner space ofpick, directly by the source of acoustic performance.
 8. Hydraulic pickaccording to claim 1, is in stop position safely kept by gas pressuresingle-shot led into gas chamber.
 9. Hydraulic pick according to claim1, is equipped by safety circuit made from drilling from the surface tothe inner space of piston rod, which is connected with inlet channel andwith return duct, whereby into drilling is inserted movable carpel. 10.Hydraulic pick according to claim 1, is equipped by safety circuit madefrom second tap, safety chamber and return tap, whereby the second tapis led from the surface of piston rod into inlet channel in it, returntap is led from the surface of piston rod into return duct and safetychamber is created in the upper part of striking pin from the innerside.